Process for vulcanizing rubber at a low temperature

ABSTRACT

A process for vulcanizing a rubber base comprising at least one halogen-containing amorphous polymer at a low temperature ranging from 5° to 85° C., which comprises carrying out the vulcanization in the presence of 0.01 to 20 parts by weight of an organic hydroperoxide and/or ketone peroxide per 100 parts by weight of the rubber base. 
     In the above process, at least one member selected from the group consisting of (I) the oxides of metals, such as zinc, lead, chromium, cobalt, nickel, magnesium, manganese, copper and iron, or the metallic salts of said metals with aliphatic or cycloaliphatic carboxylic acid having 8 to 24 carbon atoms; (II) methacrylic esters; (III) maleimides; and (IV) oximes, may be used as a vulcanization activator or a vulcanization accelerator in an amount of 0.01 to 20 parts by weight per 100 parts by weight of the rubber base.

This is a Continuation of application Ser. No. 655,547 filed Feb. 5,1976 now abandoned which in turn is a continuation of Ser. No. 429,588,filed Jan. 2, 1974 now abandoned.

The present invention relates to a process for vulcanizing at least onehalogen-containing amorphous polymer at a low temperature. Moreparticularly, it pertains to a process for vulcanizing at least onehalogen-containing amorphous polymer at a low temperature, in which anorganic hydroperoxide and/or ketone peroxide as a vulcanizing agent isused alone or in combination with a specific vulcanization activator oraccelerator to achieve the vulcanization at a temperature as low as from5° to 85° C.

As the known literature references concerning a low temperaturevulcanization process using an organic hydroperoxide as a vulcanizingagent, there are Japanese Pat. Nos. 19,930/67 and 16,584/70. Theserelate to amorphous copolymers consisting of ethylene, alpha-olefin andcyclic or acyclic polyene having nonconjugated double bond. There isfound no literature concerning the halogen-containing amorphous polymerswhich are the object of the present invention.

At present, halogen-containing amorphous polymers are, in many cases,used in adhesives, paints and sealants. It is greatly significant that alow temperature vulcanization be applicable to these uses. In order toattain this object, therefore, the present inventors have long doneextensive research on the low temperature vulcanization ofhalogen-containing amorphous polymers to achieve this invention. Thisinvention is characterized by using an organic hydroperoxide or ketoneperoxide as a vulcanizing agent.

An object of the present invention is to provide a process forvulcanizing halogen-containing amorphous polymers at a low temperature.

Another object of the present invention is to provide a process forvulcanizing at a low temperature halogen-containing amorphous polymers,which process is applicable to adhesives, paints and sealants.

A further object of the present invention is to provide a process forvulcanizing halogen-containing amorphous polymers at a low temperature,in which an organic hydroperoxide or ketone peroxide is used as avulcanizing agent.

A still further object of the present invention is to provide a processfor vulcanizing halogen-containing amorphous polymers at a lowtemperature, in which an organic hydroperoxide or ketone peroxide as avulcanizing agent is used together with a vulcanization activator or avulcanization accelerator.

The other objects and advantages of the present invention will becomeclear from the following description.

According to the present invention, there is provided a process forvulcanizing a rubber base comprising at least one amorphous polymer at alow temperature ranging from 5° to 85° C., which comprises carrying outthe vulcanization in the presence of 0.01 to 20 parts by weight of anorganic hydroperoxide and/or ketone peroxide per 100 parts by weight ofthe rubber base, and, if necessary, in the presence of 0.01 to 20 partsby weight of at least one vulcanization activator or acceleratorselected from the group consisting of (I) metal oxides or metallic saltsof aliphatic or cycloaliphatic carboxylic acids having 8 to 24 carbonatoms, (II) methacrylates, (III) malcimides and (IV) oximes, per 100parts by weight of the rubber base.

The halogen-containing amorphous polymers in the present inventioninclude, for example, chloroprene rubber, chlorinated polyethylene,chlorosulfonated polyethylene and chlorinated ethylene-propylene-dienerubber, and the halogens include chlorine and bromine. Chlorine is themost popular and important.

The rubber base in the present invention includes halogen-containingamorphous polymers alone, mixtures thereof and mixtures ofhalogen-containing amorphous polymer and halogen-free amorphouspolymers. More particularly, it includes not only a mixture obtained bymixing the halogen-containing amorphous polymer with the halogen-freeamorphous polymer for the purpose of enhancing the weather resistanceand heat resistance and reducing the cost of the halogen-containingamorphous polymer but also a mixture obtained by mixing the halogen-freeamorphous polymers with the halogen-containing amorphous polymer for thepurpose of enhancing the tackiness and adhesiveness of the halogen-freeamorphous polymer or imparting flame-proof property to the halogen-freeamorphous polymer. In other words, it is indispensable for the rubberbase described herein to comprise at least one halogen-containingamorphous polymer. The halogen-free amorphous polymers include, forexample, styrene-butadiene rubber, ethylene-propylene-diene rubber andnatural rubber. Further, the halogen-free amorphous polymers used forthe present invention include low molecular weight amorphous copolymerssuch as low molecular weight ethylene-propylene rubber, too.

The organic hydroperoxides and ketone peroxides used in the presentinvention include, for example, alpha-cumyl hydroperoxide, tertiarybutyl hydroperoxide, p-menthane hydroperoxide,m,p-diisopropylbenzene-monohydroperoxide, methyl ethyl ketone peroxide,methyl isobutyl ketone peroxide, acetylacetone peroxide, and the like.

Another great feature of the present invention is that at least onecompound belonging to the following groups may be used as avulcanization activator or a vulcanization accelerator to adjust thevulcanization velocity:

(I) The oxides of metals such as zinc, lead, chromium, cobalt, nickel,magnesium, manganese, copper and iron; and the metallic salts of thesemetals with aliphatic or cycloaliphatic carboxylic acids having 8 to 24carbon atoms.

The aliphatic or cycloaliphatic carboxylic acid having 8 to 24 carbonatoms mentioned in group (I) include, for example, n-octoic acid,naphthenic acid, abietic acid, lignoceric acid and 2-ethylhexanoic acid.

(II) Methacrylic esters such as ethylene dimethacrylate, 1,3-butylenedimethacrylate, triethylolpropane trimethacrylate, and the like.

(III) Maleimides such as N,N'-m-phenylene bismaleimide, phenylmaleimide, and the like.

(IV) Oximes such as p-quinone dioxime, p,p'-dibenzoyl quinone dioxime,and the like.

In the present invention the vulcanizing agent is used in an amount of0.01 to 20 parts by weight, preferably 0.5 to 15 parts by weight per 100parts by weight of the rubber base. The vulcanization activator or thevulcanization accelerator is used in an amount of 0.01 to 20 parts byweight, preferably 0.1 to 10 parts by weight per 100 parts by weight ofthe rubber base. The respective quantities of the vulcanizing agent andthe vulcanization activator or the vulcanization accelerator are decideddepending upon the application and the object. In general, thevulcanization velocity is somewhat accelerated with an increase inamount of these compounding agents. Further, when the vulcanizing agentand the vulcanization activator or accelerator are liquid, they can beapplied as they are, or when they are solid, in the form of solutions inproper organic solvents, to the surface of an objective to be vulcanizedby spraying or brushing. Accordingly, it is not always necessary to usethem in admixture with the rubber base, fillers or other compoundingagents.

The rubber base usable for the present invention may contain variousfillers such as carbon black, talc, calcium carbonate, etc.; varioushigher fatty acids; coloring agents; anti-oxidants; ultravioletabsorbers; and softening agents including mineral oils.

By using the process of the present invention, there can be producedvarious rubber products, sheets, roofings, sealants, adhesives, paints,and the like.

Referring to Examples, the present invention is further illustrated, butshould not be interpreted to be limited thereto.

EXAMPLE 1

Using chloroprene rubber as the halogen-containing amorphous polymer,examination was made on the representative vulcanization system with orwithout vulcanization activator or accelerator. The result thereof isshown below.

Composition

    ______________________________________                                        Chloroprene rubber                                                            (Raw rubber Mooney                                                            viscosity, ML.sub.1+4 = 47(100° C.);                                                       100    parts by weight                                    density = 1.23)                                                               SRF carbon black    50     parts by weight                                    Zinc oxide          5      parts by weight                                    Stearic acid        1      parts by weight                                    Naphthenic oil      10     parts by weight                                    Alpha-cumyl hydroper-                                                         oxide (Concentration:                                                                             7      parts by weight                                    70% by weight)                                                                Vulcanization accelerator                                                                         2      parts by weight                                    ______________________________________                                    

Test Method

The above-mentioned materials were blended in a mixing roll and formedinto a sheet with a thickness of 1 mm, which was then allowed to standat 40° C. After a given time, the sheet was subjected to measurement oftensile strength and elongation according to JIS K-6301 (JIS is anabbreviation of Japan Industrial Standards) to examine the vulcanizationstate. The result obtained is as shown in Table 1.

                  Table 1                                                         ______________________________________                                               Vulcanization                                                                 Accelerator                                                                             p-Quinone   Ethylene                                                --        dioxime     dimethacrylate                                          Characteristics                                                        Vulcanization                                                                          T.sub.B  E.sub.B                                                                              T.sub.B                                                                              E.sub.B                                                                            T.sub.B                                                                              E.sub.B                           time (day)                                                                             (kg/cm.sup.2)                                                                          (%)    (kg/cm.sup.2)                                                                        (%)  (kg/cm.sup.2)                                                                        (%)                               ______________________________________                                        1        27       930    18     1120 50     730                               3        37       700    46     910  68     450                               6        36       710    71     710  77     330                               ______________________________________                                         Note:                                                                         T.sub.B : Tensile strength at break                                           E.sub.B : Elongation at break                                            

EXAMPLE 2

Examination was made on a chlorinated ethylene-propylene-diene rubber asthe halogen-containing amorphous polymer. The result thereof is shownbelow.

Composition

    ______________________________________                                        Chlorinated ethylene-                                                         propylene-diene rubber                                                                            100    parts by weight                                    HAF carbon black    50     "                                                  Zinc oxide          5      "                                                  Stearic acid        1      "                                                  Naphthenic oil      10     "                                                  Alpha-cumyl hydroper-                                                         oxide (Concentration:                                                                             7      "                                                  70% by weight)                                                                Vulcanization accelerator                                                                         2      "                                                  ______________________________________                                    

The above chlorinated ethylene-propylene-diene rubber was obtained bychlorinating an ethylene-propylene-5-ethylidene-2-norbornene rubberhaving a raw rubber Mooney viscosity of ML₁₊₄ =40(100° C.), an iodinevalue of 12 and a propylene content of 50% by weight, to a chlorinecontent of 25% by weight.

Test Method

The same test method as in Example 1 was repeated. The result obtainedis shown in Table 2.

                  Table 2                                                         ______________________________________                                        Vulcanization              p-Quinone                                          accelerator  --            dioxime                                                         T.sub.B   E.sub.B T.sub.B E.sub.B                                Characteristics                                                                            (Kg/cm.sup.2)                                                                           (%)     (Kg/cm.sup.2)                                                                         (%)                                    ______________________________________                                        Vulcanization                                                                            1     12        570    12     570                                  time (day)                                                                               5     18        820    24     640                                            10     30        870    45     650                                            20     65        730   135     470                                            30     103       570   165     430                                  ______________________________________                                    

EXAMPLE 3

Using chloroprene rubber, examination was made on metal oxides and metalsalts of higher fatty acids as the vulcanization accelerator oractivator. The result obtained is shown below.

Composition

The same as in Example 1, except that the amounts of vulcanizatonaccelerator added are as shown in Table 3.

Test Method

The same as in Example 1. The result obtained is shown in Table 3.

                                      Table 3                                     __________________________________________________________________________                           Chro- *                                                              Cobalt*                                                                            Iron*                                                                             mium                                                                              Cobalt*                                                                            Magne-                                                                             Lead      Magne-(*)                      Vulcanization naphth-                                                                            naph-                                                                             naph-                                                                             abie-                                                                              sium mono-                                                                             Cobalt*(*)                                                                          sium                           accelerator   enate                                                                              thenate                                                                           thenate                                                                           tate oxide                                                                              oxide                                                                             abietate                                                                            oxide                          Amount (phr)  1    1   1   1    10   10  10    10                             __________________________________________________________________________    Characte-                                                                           Vulca-                                                                  ristics                                                                             niza-                                                                         tion                                                                          time                                                                          (day)                                                                         1   27  105  57  44  82   44   32  9     15                             T.sub.B                                                                             3   37  118  72  46  103  81   47  7     21                             (kg/cm.sup.2)                                                                       5   36  100  72  50  101  91   46  8     19                                   12  38  102  76  54  110  98   61  11    20                             E.sub.3                                                                             1   930 590  860 880 780  780  850 1110  690                            (%)   3   700 420  630 630 560  580  610 1150  690                                  5   700 380  590 600 500  490  580 1000  620                                  12  550 340  390 490 400  420  490 1150  680                            __________________________________________________________________________     *Metal content: 5% by weight                                                  (*)Referential Example: alpha-cumyl hydroperoxide was not mixed.         

Example 3 fully proves the necessity of alpha-cumyl hydroperoxide as thevulcanizing agent and the effect of the oxides of these metals or thesalts of these metals with higher fatty acids as the vulcanizationaccelerator or activator.

EXAMPLE 4

Examination was made on the effect of a vulcanization accelerator uponchloroprene at 40° C. and 70° C. The result thereof is shown below.

Test Method

The same as in Example 1. The result obtained is shown in Table 4.

                                      Table 4                                     __________________________________________________________________________                                     Ethylene                                                                            N,N'-m-                                Vulcanization        --    p-Quinone                                                                           dimetha-                                                                            phenylene                                                                            Cobalt                          accelerator                dioxime                                                                             crylate                                                                             bismaleimide                                                                         abietate                        __________________________________________________________________________             Chloroprene                                                                   rubber                                                                        (Raw Rubber Mooney                                                                        100   100   100   100    100                                      visusity,                                                                     ML.sub.1+4 = 47 (100° C.);                                             Density = 1.23)                                                      Composition)                                                                           SRF carbon black                                                                          50    50    50    50     50                              (part by weight)                                                                       Naphthenic oil                                                                            10    10    10    10     10                                       Zinc oxide  5     5     5     5      5                                        Stearic acid                                                                              1     1     1     1      1                                        Alpha-cumyl 7     7     7     7      7                                        hydroperoxide                                                                 Vulcanizaton                                                                  accelerator 0     2     2     2      1                               __________________________________________________________________________    Vulcanization                                                                 temperature (° C.)                                                                          40 70 40 70 40 70 40 70 40 70                            __________________________________________________________________________           Vulcan-                                                                             1       38 105                                                                              50 111                                                                              66 102                                                                              76 118                                                                              77 123                           T.sub.B      3       53 114                                                                              59 134                                                                              58 110                                                                              94 130                                                                              106                                                                              128                                  zation                                                                              6       55 102                                                                              56 141                                                                              55 108                                                                              98 144                                                                              102                                                                              119                           (kg/cm.sup.2)                                                                              9       56 106                                                                              61 136                                                                              61 -- 87 128                                                                              110                                                                              --                                   time (day)                                                                          15      58 -- 69 -- 65 -- 94 -- 108                                                                              --                                   Vulcani-                                                                            1       890                                                                              380                                                                              870                                                                              320                                                                              520                                                                              270                                                                              560                                                                              160                                                                              600                                                                              300                           E.sub.B      3       740                                                                              280                                                                              880                                                                              280                                                                              470                                                                              310                                                                              390                                                                              160                                                                              450                                                                              310                                  zation                                                                              6       650                                                                              230                                                                              850                                                                              240                                                                              440                                                                              210                                                                              230                                                                              140                                                                              430                                                                              250                           (%)          9       680                                                                              220                                                                              810                                                                              240                                                                              400                                                                              -- 290                                                                              130                                                                              360                                                                              --                                   time (day)                                                                          15      600                                                                              -- 710                                                                              -- 380                                                                              -- 240                                                                              -- 350                                                                              --                            __________________________________________________________________________

EXAMPLE 5

Examination was made on the effect of carbon black upon the lowtemperature vulcanization of the same chlorinatedethylene-propylene-diene rubber as in Example 2. The result thereof isgiven below.

Composition

    ______________________________________                                        Chlorinated ethylene-                                                         propylene-diene rubber                                                                           100    parts by weight                                     Carbon black       50     "                                                   Naphthenic oil     5      "                                                   Zinc oxide         5      "                                                   Stearic acid       1      "                                                   Alpha-cumyl                                                                   hydroperoxide      7      "                                                   p-Quinome dioxime  2      "                                                   ______________________________________                                    

Test Method

The same as in Example 1. The result obtained is shown in Table 5.

                  Table 5                                                         ______________________________________                                        Kind of carbon black                                                                           ISAF     HAF     FEF  GIF                                    ______________________________________                                                           1      13     9     11    8                                T.sub.B Vulcani-   6      15     14    13    11                               (kg/cm.sup.2)                                                                         zation    20     123    111   102    68                                       time                                                                          (day)     30     202    149   133   105                                       Vulcani-   1     370    350   390   450                               E.sub.B zation     6     620    650   790   760                               (%)     time      20     480    470   520   590                                       (day)     30     330    350   400   450                               ______________________________________                                    

EXAMPLE 6

Examination was made on mixtures of a halogen-containing amorphouspolymer and the halogen-free amorphous copolymer as the rubber base, inwhich chloroprene rubber was used as the halogen-containing amorphouspolymer and the same ethylene-propylene-diene rubber as in Example 2 wasused as the halogen-free amorphous copolymer.

Test Method

The same as in Example 1. The result obtained is shown in Table 6.

                                      Table 6                                     __________________________________________________________________________           Chloroprene rubber                                                     (Raw rubber Mooney viscosity,                                                        100             75  50  25  --*                                               ML.sub.1+4 = 47 (100° C.);                                             density = 1.23)                                                        Composition                                                                          Ethylene-propylene-diene rubber                                                               --  25  50  75  100                                    (part by                                                                             SRF carbon black                                                                              50  50  50  50  50                                     weight)                                                                              Naphthenic oil  10  10  10  10  10                                            Zinc oxide      5   5   5   5   5                                             Stearic acid    1   1   1   1   1                                             Alpha-cumyl hydroperoxide                                                                     7   7   7   7   7                                             Cobalt abietate 0.5 0.5 0.5 0.5 0.5                                           p-Quinone dioxime                                                                             2   2   2   2   2                                                    1        60  47  41  54  81                                     T.sub.B                                                                              Vulcanization                                                                        3        73  64  68  69  101                                    (kg/cm.sup.2)                                                                        time (day)                                                                           10       87  88  93  80  102                                                  1        780 660 510 420 340                                    E.sub.B                                                                              Vulcanization                                                                        3        530 490 490 420 350                                    (%)    time (day)                                                                           10       400 420 420 340 300                                    __________________________________________________________________________     *Referential example                                                     

EXAMPLE 7

Examination was made on the effect of vulcanizing agent upon the lowtemperature vulcanization of chloroprene rubber as thehalogen-containing amorphous polymer.

Composition

    ______________________________________                                        Chloroprene rubber                                                            (Raw rubber Mooney viscosity,                                                                     100    parts by weight                                    ML.sub.1-4 = 47 (100° );                                               density = 1.23)                                                               SRF carbon black    50     "                                                  Naphthenic oil      10     "                                                  Zinc oxide          5      "                                                  Stearic acid        1      "                                                  Cobalt abietate     0.5    "                                                  Vulcanizing agent   1/30   mole.                                              ______________________________________                                    

Test Method

The same test method as in Example 1 was repeated, except thatvulcanization was carried out at room temperature.

The result obtained is shown in Table 7.

                                      Table 7                                     __________________________________________________________________________                          m.p-Diiso-                                                            Tertiary-                                                                             propyl  p-Menthane                                                                          Methyl ethyl                              Kind of vulca-                                                                              butyl   benzene mono-                                                                         hydro-                                                                              ketene                                    nizing agent  hydrooperoxide                                                                        hydroperoxide                                                                         peroxide                                                                            peroxide                                  __________________________________________________________________________               1  35      69      61    26                                        T.sub.B                                                                            Vulcaniza-                                                                          3  45      93      82    35                                        (kg/cm.sup.2)                                                                      tion time                                                                           5  53      89      85    45                                             (day) 7  72      101     89    48                                                   10 69      105     94    58                                                   1  830     750     780   810                                       E.sub.B                                                                            Vulcani-                                                                            3  790     700     750   790                                       (%)  zation time                                                                         5  690     690     740   770                                            (day) 7  610     600     700   730                                                  10 610     500     690   690                                       __________________________________________________________________________

What is claimed is:
 1. A process for vulcanizing a non-aqueouschloroprene rubber base comprising chloroprene rubber at a lowtemperature consisting essentially ofvulcanizing said non-aqueouschloroprene rubber base at a temperature ranging from 5° to 85° C. inthe presence of 0.01 to 20 parts by weight of at least one vulcanizingagent selected from the group consisting of an organic hydroperoxide andketone peroxide per 100 parts by weight of said chloroprene rubber, and0. 01 to 20 parts by weight of at least one vulcanization activator oraccelerator selected from the group consisting of oxides of zinc, lead,chromium, cobalt, nickel, magnesium, manganese, copper, and iron per 100parts by weight of said chloroprene rubber.
 2. A process as defined inclaim 1, wherein the amount of the vulcanizing agent is in a range of0.5 to 15 parts by weight.
 3. A process as defined in claim 1, whereinthe vulcanizing agent is selected from the group consisting ofalpha-cumyl hydroperoxide, tertiary-butyl hydroperoxide, p-menthanehydroperoxide, m,p-diisopropylbenzene monohydroperoxide, methyl ethylketone peroxide, methyl isobutyl ketone peroxide and acetylacetoneperoxide.
 4. A process as defined in claim 1, wherein the vulcanizingagent is alpha-cumyl hydroperoxide.
 5. The process of claim 1 whereinsaid vulcanization activator or accelerator is zinc oxide.